The present invention relates to an inkjet recording method and an inkjet recording apparatus.
1. Prior Art
Inkjet recording, in which fine droplets of ink are flown by means of various principles to be adhered on a recording medium and such as images and letters are recorded, has advantages of easiness of relatively high speed, low noise and multi-colored recording.
Further, higher image quality comparable to silver halide photography and a lower price of an apparatus in inkjet printing with dye ink, due to advances of technologies, are accelerating the pervasion.
A dye is soluble in a solvent and a dye molecule is colored in a molecular state or in a cluster state. Therefore, the absorption spectrum is sharp and exhibits a color of high purity and brightness due to similar environment of each molecule. Further, transparency is high and hue is bright because there is no particle property, and no generation of light scattering and light reflection.
However, on the other hand, since decrease of a number of molecules directly reflects a color density when molecules are destructed by such as a photochemical reaction, light fastness is poor. Inkjet recorded images are excellent in image quality, however, show significant deterioration of image quality by aging, and it is a present stage that no techniques exceeding silver salt photography in respect to image storage stability.
In contrast to dye ink, pigment ink that uses a pigment being excellent in light fastness as a colorant has been utilized, as ink for the purpose of requiring an image being tough against photo-fading. A pigment is insoluble in a solvent and a dye molecule forms a particle to contribute coloring in a state of being dispersed. Even when a molecule at the surface was destroyed by such as a photochemical reaction, apparent decrease of coloring strength was small to exhibit an excellent image storage stability, however, gloss was significantly decreased due to the effects of light scattering and light reflection caused by particles.
As a method to solve the above-described problem, a method, in which thermoplastic fine particles, basically comprised of a thermoplastic resin, are melt to be formed into a film on an ink receiving layer to provide water resistance and gloss, is disclosed in Japanese Patent Publication No. 2-31673.
However, in inkjet printers available on the market, improvement of an ink absorption property of a recording medium has been desired in accordance with increase of printing speed, increase of recording density and improvement of required image density for photographic tone images, and the above-described technique can be said insufficient in this respect.
Further, a technique in which pigment particles are migrated into a thermoplastic resin layer after recording with pigment ink containing no dispersant on a recording medium having an outermost layer comprised of a thermoplastic resin, is disclosed in JP-A No. 11-208097 (hereinafter, JP-A refers to Japanese Patent Publication Open to Public Inspection). After pigment ink is adhered on the surface of a recording material, pigment particles are present on the surface of a thermoplastic resin layer and a solvent component is absorbed by each layer constituting an image receiving medium.
Particularly, in a higher density portion, pigment particles are distributed densely on the surface of a recording material irrespective of the presence of a dispersant in pigment ink. Therefore, significant decrease of gloss was observed as described above.
Further, in JP-A No. 2000-203152, a proposal is disclosed to improve an ink absorption property by defining a particle diameter of thermoplastic resin fine particles utilized in an ink receiving layer to be not less than 1 μm, however, by such large particles, film formation by melting is not performed sufficiently, and only images having poor gloss can be obtained, in addition, it is also difficult to achieve ink absorption amount and speed similar to those of inorganic fine particles.
Further, in JP-A No. 2000-280603, an inkjet recording medium containing thermoplastic resin fine particles and colloidal silica of 30 weight % thereof is proposed, however, it can be said insufficient in a today's trend requiring higher printing speed.
Further, in the above-described each recording medium, it can hardly be said sufficient with respect to quality requiring both abrasion resistance and water resistance due to insufficient film formation of thermoplastic resin fine particles and insufficient minuteness of a film.
Further, in JP-A No. 2002-178623, an image forming method, in which graininess and image storage stability has been improved by including thermoplastic fine particles in a surface layer and being subjected to a heating and pressing treatment after recording with pigment ink, is disclosed, however, it cannot be said sufficient quality in the stage of recent years when further improvement of printing speed is required.
Further, in JP-A No. 2002-67295, an inkjet recording apparatus; which is provided with a head ejecting ink on an image receiving sheet comprised of an ink receiving layer containing thermoplastic resin fine particles on the surface layer and a solvent absorbing layer inside thereof, and a heating means, and having a heating and pressing time of from 0.1 to 2 seconds, a temperature of from 50 to 150° C. and a pressure of from 9.8×104 to 4.9×106 Pa; is disclosed. According to the method, it is said that an image having improved gloss can be obtained by making an ink receiving layer transparent, however, it is still not satisfactory in respect to gloss and abrasion resistance to require further improvement.